--- /dev/null
+(**************************************************************************)
+(* ___ *)
+(* ||M|| *)
+(* ||A|| A project by Andrea Asperti *)
+(* ||T|| *)
+(* ||I|| Developers: *)
+(* ||T|| The HELM team. *)
+(* ||A|| http://helm.cs.unibo.it *)
+(* \ / *)
+(* \ / This file is distributed under the terms of the *)
+(* v GNU General Public License Version 2 *)
+(* *)
+(**************************************************************************)
+
+include "basic_2A/notation/relations/pconvstar_4.ma".
+include "basic_2A/conversion/cpc.ma".
+
+(* CONTEXT-SENSITIVE PARALLEL EQUIVALENCE ON TERMS **************************)
+
+definition cpcs: relation4 genv lenv term term ≝
+ λG. LTC … (cpc G).
+
+interpretation "context-sensitive parallel equivalence (term)"
+ 'PConvStar G L T1 T2 = (cpcs G L T1 T2).
+
+(* Basic eliminators ********************************************************)
+
+lemma cpcs_ind: ∀G,L,T1. ∀R:predicate term. R T1 →
+ (∀T,T2. ⦃G, L⦄ ⊢ T1 ⬌* T → ⦃G, L⦄ ⊢ T ⬌ T2 → R T → R T2) →
+ ∀T2. ⦃G, L⦄ ⊢ T1 ⬌* T2 → R T2.
+normalize /3 width=6 by TC_star_ind/
+qed-.
+
+lemma cpcs_ind_dx: ∀G,L,T2. ∀R:predicate term. R T2 →
+ (∀T1,T. ⦃G, L⦄ ⊢ T1 ⬌ T → ⦃G, L⦄ ⊢ T ⬌* T2 → R T → R T1) →
+ ∀T1. ⦃G, L⦄ ⊢ T1 ⬌* T2 → R T1.
+normalize /3 width=6 by TC_star_ind_dx/
+qed-.
+
+(* Basic properties *********************************************************)
+
+(* Basic_1: was: pc3_refl *)
+lemma cpcs_refl: ∀G,L. reflexive … (cpcs G L).
+/2 width=1 by inj/ qed.
+
+(* Basic_1: was: pc3_s *)
+lemma cpcs_sym: ∀G,L. symmetric … (cpcs G L).
+normalize /3 width=1 by cpc_sym, TC_symmetric/
+qed-.
+
+lemma cpc_cpcs: ∀G,L,T1,T2. ⦃G, L⦄ ⊢ T1 ⬌ T2 → ⦃G, L⦄ ⊢ T1 ⬌* T2.
+/2 width=1 by inj/ qed.
+
+lemma cpcs_strap1: ∀G,L,T1,T,T2. ⦃G, L⦄ ⊢ T1 ⬌* T → ⦃G, L⦄ ⊢ T ⬌ T2 → ⦃G, L⦄ ⊢ T1 ⬌* T2.
+normalize /2 width=3 by step/
+qed-.
+
+lemma cpcs_strap2: ∀G,L,T1,T,T2. ⦃G, L⦄ ⊢ T1 ⬌ T → ⦃G, L⦄ ⊢ T ⬌* T2 → ⦃G, L⦄ ⊢ T1 ⬌* T2.
+normalize /2 width=3 by TC_strap/
+qed-.
+
+(* Basic_1: was: pc3_pr2_r *)
+lemma cpr_cpcs_dx: ∀G,L,T1,T2. ⦃G, L⦄ ⊢ T1 ➡ T2 → ⦃G, L⦄ ⊢ T1 ⬌* T2.
+/3 width=1 by cpc_cpcs, or_introl/ qed.
+
+(* Basic_1: was: pc3_pr2_x *)
+lemma cpr_cpcs_sn: ∀G,L,T1,T2. ⦃G, L⦄ ⊢ T2 ➡ T1 → ⦃G, L⦄ ⊢ T1 ⬌* T2.
+/3 width=1 by cpc_cpcs, or_intror/ qed.
+
+lemma cpcs_cpr_strap1: ∀G,L,T1,T. ⦃G, L⦄ ⊢ T1 ⬌* T → ∀T2. ⦃G, L⦄ ⊢ T ➡ T2 → ⦃G, L⦄ ⊢ T1 ⬌* T2.
+/3 width=3 by cpcs_strap1, or_introl/ qed-.
+
+(* Basic_1: was: pc3_pr2_u *)
+lemma cpcs_cpr_strap2: ∀G,L,T1,T. ⦃G, L⦄ ⊢ T1 ➡ T → ∀T2. ⦃G, L⦄ ⊢ T ⬌* T2 → ⦃G, L⦄ ⊢ T1 ⬌* T2.
+/3 width=3 by cpcs_strap2, or_introl/ qed-.
+
+lemma cpcs_cpr_div: ∀G,L,T1,T. ⦃G, L⦄ ⊢ T1 ⬌* T → ∀T2. ⦃G, L⦄ ⊢ T2 ➡ T → ⦃G, L⦄ ⊢ T1 ⬌* T2.
+/3 width=3 by cpcs_strap1, or_intror/ qed-.
+
+lemma cpr_div: ∀G,L,T1,T. ⦃G, L⦄ ⊢ T1 ➡ T → ∀T2. ⦃G, L⦄ ⊢ T2 ➡ T → ⦃G, L⦄ ⊢ T1 ⬌* T2.
+/3 width=3 by cpr_cpcs_dx, cpcs_strap1, or_intror/ qed-.
+
+(* Basic_1: was: pc3_pr2_u2 *)
+lemma cpcs_cpr_conf: ∀G,L,T1,T. ⦃G, L⦄ ⊢ T ➡ T1 → ∀T2. ⦃G, L⦄ ⊢ T ⬌* T2 → ⦃G, L⦄ ⊢ T1 ⬌* T2.
+/3 width=3 by cpcs_strap2, or_intror/ qed-.
+
+(* Basic_1: removed theorems 9:
+ clear_pc3_trans pc3_ind_left
+ pc3_head_1 pc3_head_2 pc3_head_12 pc3_head_21
+ pc3_pr2_fqubst0 pc3_pr2_fqubst0_back pc3_fqubst0
+ pc3_gen_abst pc3_gen_abst_shift
+*)
+(* Basic_1: removed local theorems 6:
+ pc3_left_pr3 pc3_left_trans pc3_left_sym pc3_left_pc3 pc3_pc3_left
+ pc3_wcpr0_t_aux
+*)